Intel is set to shift into overdrive when the new ‘Nehalem' microarchitecture is released towards the end of this year. A radical revision of the current Core microarchitecture, Nehalem will be the blueprint for almost all Intel-based computers - desktops, notebooks and servers - from 2008 until at least 2010.

Those systems will be powered by anywhere from two to eight cores on a single processor, compared to Intel's current quad-core solution of strapping two dual-cores chips together. Each individual core will be able to run two simultaneous threads and sitting atop the per-core Level 2 cache will be a shared slab of Level 3 cache accessible to all cores.

(Nehalem derives its codename from the river of the same name in Orgeon, close to Intel's centre where the architecture and companion next-gen processors were designed. It'll get a real name closer to launch, and we're tipping it to be christened as ‘Core 3'. While the current microarchitecure is officially just called Core,the processors built on that foundation are now known as Core 2. Nehalem provides Intel with what must be a welcome chance to clean up the resulting brand confusion)

"First the tick, now the tock" said Stephen Smith, Intel VP and director of the Digital Enterprise Group, referring to Intel's strategy of delivering processors and microarchitecture in alternate steps across a two year cycle.

"For the beginning of each silicon generation we have a processor that's derived from the prior generation, and that's the tick. Then we have a product that's the larger step, what we call the tock, which is a new microarchitecture to really bring on a leadership level of performance."

Last year's 45nm Penryn processor was the tick, and now Intel is gearing up for the tock as Nehalem, which Smith describes as "our ground-up new design optimised for 45nm technology".

Beyond its mandatory newer-faster-better bits of technology, Nehalem is "a scalable design", explains Smith. "It uses a number of building blocks that allows us to build different product configurations, so we can compose various products out of these blocks. Four core is the first to go into production, we also expect to build a monolithic eight core design in 2009 with additional bandwidth."

Just don't go looking for a single core Nehalem chip: that's now ancient history, says Smith. "The lowest implementation we have in mind is a two core design".

Among those building blocks are two new pieces of processor plumbing: an integrated memory controller and a dedicated CPU pipeline called QuickPath Interconnect. Well, they're new for Intel, although AMD already employs both features (for QuickPath Interconnect, read ‘HyperTransport') as well as Level 3 cache. In those areas, Nehalem is very much Intel's catch-up ploy.

Nehalem's memory controller will sit on the individual processor die rather than an external ‘northbridge' hub and support only DDR3 (DDR2 chips need not apply) with three memory channels per socket to further boost memory bandwidth and reduce latency.

This in turn allows Intel to re-engineer Nehalem's caching. Level 2 cache has been promoted from being per-processor to per-core, but the efficiency of the integrated controller allows this L2 cache to be substantially downsized to just 256Kb for each core. A fat Level 3 cache starting at 4MB is shared by all cores in the processor.

A key difference in the approaches of AMD and Intel is that Intel's Level 3 ‘inclusive cache hierarchy' dictates that any data sitting in the per-core L1 or L2 caches must also be present in the shared L3 cache. "If one core needs a piece of data it only has to go as far as checking Level 3, because all the data from all cores is sitting in Level 3" explains Ronak Singhal, one of Nehalem's lead engineers. "There's no latency in fetching data direct from the other core caches".

The size of the L3 cache "will depend on the number of cores in the product" says Singhal. It's expected that the dual-core Nehalem processors will start with 4MB of L3 cache, quad-cores will get 8MB and the eight-core servers could get as much as 24MB to play with.

The other key piece of plumbing for multi-processor systems is QuickPath Interconnect, which provides a dedicated pathway between CPU sockets in order to boost dataflow between processors, as well as running between the CPU and the IO hub.

The modular design of Nehalem considers QPI as just another building blocks, allowing Intel to configure high-end systems with multiple QPI pathways.

So when can we expect all this geeky goodness? Intel signed off on Nehalem's design last year and the first silicon hits production in fourth quarter of the year. The only product at launch will be a six-core server powerplant.

Things hot up in 2009, with the arrival of the quad-core ‘Bloomfield' desktop chip within the first three months, followed in Q2 by mainstream dual-core desktop (Havendale) and mobile (Auburbdale) processor plus a quad-core extreme mobile chip (Clarksfield).

Nehalem will also be the foundation underpinning Intel's sixth-generation Centrino platform, codenamed Calpella and due to launch in early 2009, perhaps simultaneously with the mobile processors. (The fifth-gen Montevina platform, now christened Centrino 2 and due around the middle of this year, will use 45nm Penryn-class processors but is built on the Core architecture.)

It sounds incrediblyimpressive... now let's hope the pricetag is low enough for normal people not to sell their house just to get one of them

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XDude [ Wed Mar 19, 2008 3:37 am ]

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we all know what the price tag looks like for intel products.
looking forward to atleast $250 for a decent core 3. Quads would cost a bit more and the octos would come later, problary around the $500-$800 range.

I still need to get my hands on those extreme edition, even the X6850 on ebay cost ~$700. Man, when will those extremes drop in price.

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Frozenport [ Wed Mar 19, 2008 3:46 am ]

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If they were smart, they would kill AMD now by introducing unique instruction sets or adding a co-processor...

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fzajac [ Wed Mar 19, 2008 1:26 pm ]

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Frozenport wrote:

If they were smart, they would kill AMD now by introducing unique instruction sets or adding a co-processor...

IMHO, AMD is already almost dead. Their marketing is dead and they mean less and less on the hardware's market. Also, they wasted a chance to get a better possition after eating ATi...
I was always an Intel fanboy but i don't think it's good situation now. If Intel will stay as the only good and known CPUs manufacter (what will be soon, i think) they may (and propably will) rise the prices more and more (of course it's not instant process and will request few years of very good marketing)...
That's only my opinion...

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mrpijey [ Sat Mar 29, 2008 12:36 am ]

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Oh ye of little faith...

AMD is soo not dead. Only because they had a bad run with their Phenom gen CPU:s doesn't mean they are going to crash. AMD has been here before, and they managed. Remember, AMD is still doing very good in the mid-low segment. And now that AMD owns ATI they also have the entire GPU market ATI has, which is quite big. Perhaps not on the high-end part of the scale, but think OEM. When it comes to laptop chips AMD is huge there, in some parts of the world way bigger than Intel.

So AMD will stay afloat as they did before (remember the K6 era?). Sure the ATI/AMD merger took a deep cut in their money bags, but it was a smart move. With the upcoming GPU-on-a-CPU tech AMD will have a great thing there. AMD is also doing fairly good on the server market. AMD is the favorite underdog

Only because AMD failed one chip gen doesn't mean they will crash and burn.